These connectors are used, inter alia, to make connections between electrical appliances, and provide the interconnections between wire harnesses used in automobiles, industrial building machinery and elsewhere. In general, waterproof electrical connectors comprise a housing made from a synthetic resin material, a terminal-accommodation chamber formed in the housing, a terminal fixed to the end of an electrical wire and accommodated in the terminal-accommodation chamber, and a waterproof plug fixed to the end of the electrical wire as well as the terminal (see for example Laid-open Japanese Patent Application Hei 4-65074 and Laid-open Japanese Utility Model Sho 63-69373).
The above-mentioned waterproof plug is formed with a larger diameter than the terminal. An opening is formed in the housing on the insertion side contiguous with a terminal-accommodation chamber. The insertion side opening is formed with a larger diameter than the terminal-accommodation chamber and defines a peripheral surface for sliding contact with the outer circumferential surface of the waterproof plug. In use, the terminal is inserted via the insertion side opening into the terminal-accommodation chamber and is fixed in the-housing by what is termed a lance. By inserting the terminal piece into the housing from the insertion side opening, the waterproof plug seals the insertion side opening.
In the process of making such a connector, it is usual to check for correct installation of the terminal. The inspection checks such aspects as whether the terminal is inserted correctly in the housing and has been engaged by the lance and whether the crimping of the wire on to the terminal has been well effected. This is because the performance of a product using the connector will be defective if a terminal has not been inserted, if the insertion of the terminal is incomplete, or if the crimping of the electrical wire is poor.
Inspecting devices for checking the passage of the terminal are disclosed, for example, in Laid-Open Japanese Utility Model Application Sho 57-89964. Published Japanese Utility Model Sho 55-8221, Laid-open Japanese Utility Model Application Sho 64-27668, and Laid-open Japanese Patent Applications Hei 5-26939, Hei 5-288793 and Hei 5-234660.
These devices are equipped with a stopping means for holding the connector housing in a predetermined inspection position, and detectors which press resiliently onto the terminals inside the housing so held. The above-mentioned detectors are arranged in such a way that they are urged in the direction opposite the direction in which the terminal is inserted by means of an urging member, and that the displacement position can be sensed by means of a sensor.
When the terminals are properly installed in the housing, the detectors are pushed in the terminal insertion direction, overcoming the urging force of the urging member, and the sensor senses the correct installation of the terminal. If a terminal is not inserted in the housing, or is not engaged by the lance the detector projects towards the terminal-accommodation chamber, due to the urging force of the above-mentioned urging member, and therefore the sensor is able to sense a defect in the connector. Furthermore, even when a terminal has been inserted incompletely (referred to as "semi-fitted" in this specification), the urging member pushes the terminal towards the insertion side opening and therefore the detector projects towards the terminal-accommodation chamber and can sense a defect in the connector.
However, when a connector of this configuration is inspected by the conventional connector inspecting device described above, there are occasions when the semi-fitted state cannot be detected reliably. This is because where waterproof connectors are concerned, and particularly when a large-diameter waterproof plug is used, the larger the surface area of compressed contact between the waterproof plug and the insertion side opening, the larger will be the frictional resistance thereof, and the displacement of the detector by the urging member will be limited.
In particular, this is because, when a dual arrest structure is adopted in which the terminal is directly or indirectly held in the housing using a retainer formed by a member separate to the housing, the holding forces are larger than the urging force (e.g. 2 kgf) of the above-mentioned urging member and the displacement of the detector is insufficient.
Furthermore, there have been proposals to set the urging force of the above-mentioned urging member at an increased level to prevent this disadvantage, but these are undesirable since in this case there are excessive loads on the terminal and the lance, as well as on the retainer, when the terminal is correctly inserted.
The present invention takes the above disadvantage into account and aims to provide an inspecting device for waterproof connectors which is able to correct semi-fitting during the inspection step.